The present invention relates to a method for monitoring a drive, in particular an electric motor, where a position and/or a speed of the drive is detected by a drive sensor and is transmitted in digitized form to a superordinate drive control unit by a feedback unit arranged at or in a housing of the drive, where at least one further measurement quantity is detected by an additional sensor arranged at or in the housing. The present invention also relates to a corresponding drive.
Methods of monitoring a drive and drives are conventional.
For the operation and the monitoring of the operation of a drive and any auxiliary devices assigned to the drive, in addition to a position and/or a speed of the drive, additional measurement quantities are often detected by additional sensors arranged at or in the housing of the drive and transmitted to the drive control unit. In this case, a number of lines between drive and drive control unit are laid per additional sensor. This is laborious and expensive. Moreover, it is often necessary to implement complicated shielding measures in order to ensure that the detected additional measurement quantities are transmitted in a manner free from interference.
An object of the present invention is to provide a method for monitoring a drive and a drive corresponding thereto by which simple, cost-effective transmission of the detected additional measurement quantities to the drive control unit is enabled, with the interference immunity of the data transmission being increased at the same time.
This object is achieved for a method according to the present invention by the fact that the at least one additional measurement quantity is transmitted to the drive control unit by the feedback unit in digitized form. This is advantageous because the feedback unit and the connection between it and the drive control unit are present in any case.
With respect to the drive according to the present invention, an additional sensor is connected to the feedback unit. This means that the detected additional measurement quantity can then be transmitted to the drive control unit via the feedback unit.
If the drive sensor and the feedback unit are combined to form an installation unit, a particularly compact structure results for drive sensor and feedback unit.
The at least one additional measurement quantity may be, e.g., a temperature prevailing in the drive, a drive vibration, a drive acceleration or a drive cooling state. It is also possible to detect a plurality of the measurement quantities mentioned and/or additional measurement quantities that are not individually enumerated here.
It is also possible for the at least one additional measurement quantity to be an auxiliary device state of an auxiliary device, e.g., a tool clamping device, assigned to the drive. In this case, therefore, a measurement quantity of an application-related additional unit, which is not necessary for operation of the drive as such, is detected. One example of such a measurement quantity is a position of the auxiliary device.
It is possible to transmit the position and/or the speed of the drive and the additional measurement quantity to the feedback unit already in digitized form. However, the position and/or the speed of the drive and the at least one additional measurement quantity may be digitized by the feedback unit.
The equipment outlay can be kept particularly low if the position and/or the speed of the drive and the at least one additional measurement quantity are fed via a multiplexer to a common A/D converter in the feedback unit.
The position and/or the speed of the drive and the at least one additional measurement quantity may have distinctly different signal levels. Therefore, the measurement accuracy can be improved if the position and/or the speed of the drive and the at least one additional measurement quantity are passed via a variable-gain amplifier between the multiplexer and the A/D converter in the feedback unit, and the gain is set so that the A/D converter is driven at a full level, but is not overdriven.
If the position and/or the speed of the drive and the at least one additional measurement quantity are transmitted serially to the drive control unit by the feedback unit, only a very small number of lines have to be laid between feedback unit and drive control unit.
If the position and/or the speed of the drive are transmitted with high priority, and the at least one additional measurement quantity with low priority, to the drive control unit, the transmission of the at least one additional measurement quantity has no, or only a small, influence on the regulating dynamic range of the drive.